The ER membrane is 2.5 nm thick. How many amino acids with mostly hydrophobic character does a protein have to have in a domain that can span the membrane as an alpha helix

b would be the right answer

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.

a=c and then d= c because of the band so you get ac/dc and you add them together you get sound waves